Class blog for Anth 249: Evolution and human disease. We will be responding to class readings and engaging with the wider network of blogs and online content on evolutionary medicine. We might also make up some fun projects along the way.

Tuesday, March 26, 2013

Respondent Post: Evolutionary Selection of Hormone Levels

In response to Heather's inquiry of the natural selection process of high hormone levels in women, I'd like to start by saying she brings up a good point of how counter intuitive the lack of selecting against high hormonal levels appears. However, I think it is important to also keep in mind the pace at which we have usually observed natural selection and evolution to occur and compare it to the rate at which human culture changes. Within the past several hundred years alone (let alone this decade), mankind and the earth has witnessed great changes environmentally, biologically, and culturally. These factors together play key roles in affecting one another's influence and speed at which it occurs. It is very likely that natural selection choosing against these traits is and has been occurring, but far too slow for anyone to yet notice. Or perhaps, Mother Nature is more clever than she appears and has a plan in not selecting against high hormonal levels in women. In other words, lately females in more developed countries have been living longer and able to have more healthier offspring. Could it be that these benefits from living in a westernized/modernized nation outweigh the potential negative health costs summoned by high insulin and hormonal levels? The trade-off between the two is one possessing great uncertainty--uncertainty natural selection wants to avoid. At this point, there doesn't seem a way to know for sure without the impact of confounding variables. More difficulty in deciphering this puzzle is centered in the drastic differences in styles of living of individuals in less developed countries, compared to "modern" nations. They too, have witnessed longer life spans, and healthier births (but at a rate far slower than developed countries, that it may have been viewed as negligible by many). So, at this point in the world's development and growth, it is inevitable to say, "only time will tell". A long time. But in the end, natural selection works out and reproductive success is evolution's first and foremost primary goal.